According to Brand Licensing Europe, Nickelodeon has interesting plans in store for Spongebob Squarepants sometime in 2013:

For SpongeBob, a humorous adult-targeted clothing line is on the way, including ‘Keep Calm and Gary On’ T-shirts. The ‘Dare to be Square’ marketing initiative will be ramped up in 2013, and ‘It’s a SpongeBob Christmas’ special movie will arrive in Christmas 2013, complete with computer generated imagery and its own marketing campaign, as well as a range of consumer products.

Can you see yourself in an adult-targeted Spongebob Squarepants outfit?